GPWS warning. Flight crew initiated immediate climb as per emergency procedures.

Attributes
ACN	299846
Time
Date	199503
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : sjc
State Reference	CA
Altitude	msl bound lower : 5100 msl bound upper : 6500
Environment
Flight Conditions	IMC
Light	Dusk
Aircraft 1
Controlling Facilities	tracon : oak
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 5000 flight time type : 3000
ASRS Report	299846
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 15000 flight time type : 5000
ASRS Report	299663
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance flight crew : returned to intended course or assigned course
Consequence	faa : reviewed incident with flight crew
Supplementary
Air Traffic Incident	other

Narrative:

During vectors to an ILS final to runway 12 at sjc, at 5100 ft MSL (MSA 5500 ft) on a heading of about 300 degrees we received a GPWS warning of terrain/and whoop-whoop pull up. Being in heavy WX and below MSA and not able to talk to approach at that instant, we initiated an immediate maximum power climb and leveled at 6500 ft MSL (nearest altitude we could level at after passing 5500 ft) and then advised approach we had deviated from altitude due to a GPWS warning. Even though we have both been to sjc many times and knew the terrain quite well, we were in the WX on a vector below MSA and decided in about 3-5 seconds to follow the GPWS warning just in case we might be missing something. The controller advised us later we were 'ok' since we were at his MVA, something we as cockpit crewmembers do not have. After further discussion with the controller on the ground we determined that we were flying towards terrain but it was below our altitude.

Original NASA ASRS Text

Title: GPWS WARNING. FLC INITIATED IMMEDIATE CLB AS PER EMER PROCS.

Narrative: DURING VECTORS TO AN ILS FINAL TO RWY 12 AT SJC, AT 5100 FT MSL (MSA 5500 FT) ON A HDG OF ABOUT 300 DEGS WE RECEIVED A GPWS WARNING OF TERRAIN/AND WHOOP-WHOOP PULL UP. BEING IN HVY WX AND BELOW MSA AND NOT ABLE TO TALK TO APCH AT THAT INSTANT, WE INITIATED AN IMMEDIATE MAX PWR CLB AND LEVELED AT 6500 FT MSL (NEAREST ALT WE COULD LEVEL AT AFTER PASSING 5500 FT) AND THEN ADVISED APCH WE HAD DEVIATED FROM ALT DUE TO A GPWS WARNING. EVEN THOUGH WE HAVE BOTH BEEN TO SJC MANY TIMES AND KNEW THE TERRAIN QUITE WELL, WE WERE IN THE WX ON A VECTOR BELOW MSA AND DECIDED IN ABOUT 3-5 SECONDS TO FOLLOW THE GPWS WARNING JUST IN CASE WE MIGHT BE MISSING SOMETHING. THE CTLR ADVISED US LATER WE WERE 'OK' SINCE WE WERE AT HIS MVA, SOMETHING WE AS COCKPIT CREWMEMBERS DO NOT HAVE. AFTER FURTHER DISCUSSION WITH THE CTLR ON THE GND WE DETERMINED THAT WE WERE FLYING TOWARDS TERRAIN BUT IT WAS BELOW OUR ALT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.